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<?php $arr1 = [ ['email' => 'aa@gmail.com', 'name' => 'John Doe'], ['email' => 'bb@gmail.com', 'name' => 'Johnny Sins'], ['email' => 'cc@gmail.com', 'name' => 'Jose Alvarado'] ]; $arr2 = [ ['email' => 'cc@gmail.com', 'country' => 'Japan'], ['email' => 'cc@gmail.com', 'country' => 'China'], ['email' => 'bb@gmail.com', 'country' => 'Korea'], ]; $result = array_column($arr1, null, 'email'); $counts = array_count_values(array_column($arr2, 'email')); foreach ($arr2 as $row) { if ($counts[$row['email']] > 1) { unset($result[$row['email']]); } else { $result[$row['email']] += $row; } } var_export(array_values($result));

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